ABSTRACT. We present data an ice texture, salinity, and 6 18 0 abtained fram identical sectians af ice cares during the Winter Weddell Sea Praject 1986 an RV Polarstern fram July thraugh August 1986, in the langitude range between 5 oW. and 7°E. We find no. uniquely definable relatianship between 618 0 values and ice texture in a particular sectian. Hawever, mast af the snaw ice as well as same sectians af frazil ice are faund to. have negative 6 18 0 cancentratians. This is due to. varying degrees af admixtures af metearic ice (snaw) and sea-water during farmatian af snaw ice. In cantrast to. camman assumptians, aur results seem to. indicate that a snaw caver cantributes pasitively to. sea-ice grawth rather than slawing dawn the averall grawth rate.

Ice cores obtained during October‐November 1981 from Weddell Sea pack ice were analyzed for physical, chemical, and biological parameters. Frazil ice, which is associated with dynamic, turbulent conditions in the water column, predominated (70%). Both floe thickness and salinity indicate ice which is less than 1 year old. Chemical analyses, particularly with regard to the nutrients, revealed a complex picture. Phosphate values are scattered relative to the dilution curve. Nitrate and silicate values are lower than expected from simple scaling with salinity and suggest diatom growth within the ice. Nitrite values are higher in the ice than in adjacent waters. Frazil ice formation which probably concentrates algal cells from the water column into ice floes results in higher initial chlorophyll a concentrations in the ice than in adjacent waters. This mechanical concentration is further enhanced by subsequent reproduction within the ice. Ice core chlorophyll ranged from 0.09 to 3.8 mg/m3, comparable to values previously reported for this area but significantly lower than values for Antarctic coastal fast ice. The dominance of frazil ice in the Weddell is one of the major differences between this area and others. Consequently, we believe that ice structural conditions significantly influence the biological communities in the ice.

In winter the eastern Weddell Sea in the Atlantic sector of the Southern Ocean hosts some of the most dynamic air-ice-sea interactions found on earth. Sea ice in the region is kept relatively thin by heat flux from below, maintained by upper-ocean stirring associated with the passage of intense, fast-moving cyclones. Ocean stratification is so weak that the possibility of deep convection exists, and indeed, satellite imagery from the Weddell Sea in the 1970s shows a large expanse of open water (the Weddell Polynya) that persisted through several seasons and may have significantly altered global deep-water production. Understanding what environmental conditions could again trigger widespread oceanic overturn may thus be an important key in determining the role of high latitudes in deep-ocean ventilation and global atmospheric warming. During the Antarctic Zone Flux Experiment in July and August 1994, response of the upper ocean and its ice cover to a series of storms was measured at two drifting stations supported by the National Science Foundation research icebreaker Nathaniel B. Palmer. This article describes the experiment, in which fluxes of heat, mass, and momentum were measured in the upper ocean, sea ice, and lower-atmospheric boundary layer. Initial results illustrate the importance of oceanic heat flux at the ice undersurface for determining the character of the sea ice cover. They also show how the heat flux depends both on high levels of turbulent mixing during intermittent storm events and on large variability in the stratified upper ocean below the mixed layer.

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